code: def _unsqueeze_batch(self, dim):
      x1 = self.x1.unsqueeze(dim)
      x2 = self.x2.unsqueeze(dim)
      return self.__class__(
          x1,
          x2,
          kernel=self.kernel,
          last_dim_is_batch=self.last_dim_is_batch,
          **self.params,
      )
  
imports: import functools
  from typing import Callable
  import torch
  from linear_operator import LinearOperator, to_linear_operator
  from linear_operator.utils.getitem import _noop_index
  from ..None import beta_features, settings
  from ..utils import deprecation
  from ..utils.memoize import cached
label_desc: Use image node_id 13 for calling the LazyEvaluatedKernelTensor obj's underlying member method code with example usage: obj._unsqueeze_batch(dim) and returns: self